1. Field of the Invention
The present invention relates, generally, to inoculation devices and, more particularly, to apparatus and methods used to store and preserve the sterility of inoculation devices.
2. Description of the Related Art
As the biotechnology, pharmaceutical and related industries experience unprecedented growth, their laboratory research and development proportionately expands. Thus, research precision has become increasingly important, often distinguishing their efforts. Through research evolution, research apparatus and techniques, once thought to represent the industry standard, are continually being replaced by better, more efficient and accurate apparatus and techniques.
Inoculation devices or tools are generally not considered precision research instruments. Manufacturers have not found it profitable, for example, to expend research funds to improve the precision of inoculation devices. Accordingly, significant strides to increase quantitative precision and sterile packaging of inoculation devices is greatly lacking.
Traditional laboratory inoculation techniques have remained rather crude, quantitatively inaccurate and potentially unsterile. Typically, after a desired microorganism has been successfully incubated in a nutrient broth substance, it is necessary to further colonized the micro-organism so that the particular strain can be identified, researched or experimented on. This procedure requires extracting a predetermined quantity of the inoculant from the broth and implanting or inoculating a nutrient medium, or blood agar, so that the microorganism can be grown under more controlled conditions. Using an inoculation device having an inoculating end, which is usually either needle-shaped or includes a loop end, an approximate quantity of the cultured broth is withdrawn therefrom by immersing the inoculating end in the broth. Subsequently, the inoculant is spread and implanted in the nutrient rich medium (agar) by contacting the inoculating end with the nutrient agar. Growth is stimulated by incubating the agar, for example, at approximately 37.degree. C. which simulates body conditions. This incubation period, depending on the rate of growth of the micro-organism which in some cases doubles every 20 minutes, is typically 24 hours. Subsequently, the colonized microorganism may be identified, studied or be the subject of experimentation.
Inoculation tools, in general, have not changed radically since the introduction of the inoculation loop. Earlier inoculation ends where comprised of metallic wires or needles. Often platinum or silver were used because of their higher conductive resistance. Metallic inoculation devices usually require sterilization before each use so that the inoculant is not contaminated by the growth or existence of other contaminating organisms or bacteria attached to the inoculating ends. By placing the inoculating end in an open flame, such as a bunsen burner, until the loop becomes red hot, the loop can be sterilized. The research technician must then wait for the loop to air cool so that contact with the inoculant will not kill the microorganisms therein.
Despite its crude application, metallic inoculating ends are still in use today. One problem associated with these devices is that this technique is generally time consuming. Often, several different types of microorganism colonies are being cultured consecutively. Valuable time is expended because the inoculating end must be sterilized after contact with each different inoculant or nutrient agar. Thus, the technician must complete the entire sterilization cycle after each use. Furthermore, since the metallic ends are held over an open flame, the length of the inoculating device must be fairly long to prevent conductive burning. Moreover, insulated handles are often required as a precaution and for ease of handling. Storage, however, becomes problematic when the devices are too long. Finally, materials such as platinum and silver, which are used because of their high conductive resistance, are much too costly. This cost factor is particularly important if one tries to overcome the time delay problems by using multiple metallic inoculation loops.
More recently, plastic inoculating devices have begun to replace metallic inoculating devices. While such plastic inoculation devices have decreased manufacturing costs, sterilization has become a problem. Heat sterilization over an open flame, of course, is inappropriate because the inoculating ends would either melt or substantially deform. Therefore, the inoculation devices must be sterilized by irradiation with radio-isotopes or an electron beam, or by auto-claving before packaging. Typically, a multitude of inoculating loops and needles are sterilized and then packaged in the same container. This method present many problems. Once the package is opened, the remaining inoculation devices become contaminated with time or if they are touched. Either the package must be used completely or you run the risk of inoculating future mediums with contaminated inoculants. Moreover, if the technician is not careful upon removal, the inoculating ends may become contaminated. Contact of the inoculating end against the sides of the bag is often sufficient to affect the sterility of the inoculating end.
This sterilization problem may be partially overcome by individually packaging the plastic inoculation devices and then sterilizing them. While this technique has been satisfactory for most uses, again, however, the loops often become contaminated upon removal from the bag. Moreover, removal from each individual package becomes tedious and time consuming, requiring repeated openings of individual containers. Storage also becomes problematic when these devices are amassed in bulk.
Another problem associated with plastic inoculation devices is that they tend to be extremely inaccurate. Tests have shown that the dispensing volumes of these current plastic inoculation devices may vary by as much as 60%. Part of this problem may be attributed to the techniques employed to calibrate the dispensing volume of the inoculation loop. Typically, the calibration of a dispensing volume of an inoculation loop is performed using the "Evan's Blue Dye" method. This method of calibration, although widely accepted, itself appears highly inaccurate. Thus, it is difficult to control the dispensing volume accuracy of the inoculation loop when the method employed to calibrate the dispensing volume is itself imprecise. As quantitative accuracy and research precision become increasingly desirable, this method of calibration is becoming obsolete and unacceptable. Thus, precision inoculations can be greatly compromised by these instruments.